1. Field of the Invention
The invention relates generally to an early detection and alarm system for high-profile and/or elongated cargo carried on the outside of the vehicle, such as bicycles, canoes, luggage and the like. More specifically, the invention relates to a directional sensor which is mounted directly to and removed quickly from the cargo, and which interfaces with an alarm to produce a visual and/or audible warning signal inside the passenger compartment in the event of an on-coming obstruction, such as a low overhead opening that would otherwise collide with the cargo.
2. Related Art
It is in unfortunate but an all too common occurrence when a driver returns from a journey with a tall article of cargo mounted to the vehicle top or other exterior payload area, where the cargo extends above the vehicle. The driver may forgetfully enter a garage, carport, overhang at a drive-through restaurant, or other obstruction causing the high-profile cargo to strike the opening and resulting in severe damage to the cargo, the vehicle and/or the obstruction. Because high-profile cargo transported on an exterior payload area is usually out of the driver's view, and quite often much time will have lapsed since the cargo was secured, it is entirely understandable that the driver forgets that the high-profile cargo substantially increases the overhead clearance space needed for the vehicle. This may be especially problematic with large vans and SUV's whose normal overall height may be only inches shorter than the clearance of a standard residential garage door. Thus, practically any cargo mounted to the exterior of a van or SUV is likely to exceed the garage clearance, and also place the cargo on a collision course with other obstructions.
A similar problem may exist with high-profile loads secured in the exterior payload area of a pick-up truck or utility trailer. Also, elongated objects like ladders, while not typically high-profile, can increase the length of a vehicle such that parking distance relative to a wall is affected.
The prior art has taught a variety of techniques to address this situation. Examples of passive techniques include dangling small signs from the rearview mirror as a reminder to the driver. Other passive techniques have included attaching signage inside the garage door so that when the garage door opens, the signage reminds the driver that a high-profile load is on the vehicle. U.S. Pat. No. 5,710,553 to Soares describes a passage technique wherein a laser light source is attached to the highest point of the vehicle or cargo and projects a beam of light at an elevation generally equal to the maximum height of the high-profile cargo. Aside from the inherent safety issues associated with pointing laser beams in the direction of oncoming traffic, Soares is yet another example of a passive system which can only be marginally effective because it depends upon an alert driver. In other words, if the driver fails to take note of the signage or illuminated laser spots outside the vehicle, a collision will be imminent.
Examples of active warning systems include the use of radio frequency transmitters and receivers with the transmitter being mounted in the garage and the receiver mounted upon the vehicle roof-rack or other vehicle-top structure. An example of this technique may be found in U.S. Pat. No. 6,737,960 to Preston. When a vehicle moves into range of the transmitting garage or carport, an alarm is triggered at the receiver end thus reminding the driver of the high-profile cargo so as to avoid a collision. A particular disadvantage with this technique, however, is that it is only effective when the driver approaches his or her own garage which contains the transmitting device. If the driver attempts to pull into someone else's garage, or otherwise approaches a structure with a low overhang such as might be found in a drive-through restaurant, the vehicle alarm system is not triggered.
Another example of an active warning system may be found in U.S. Publication 2004/0183661, published Sep. 23, 2004, now abandoned. Bowman discloses mounting an ultrasonic transducer to the roof of a motor vehicle and directing its sensing area at an upward angle to accommodate high-profile loads carried on its rooftop. Because the transducer is mounted to the vehicle and angled upwardly, Bowman requires a complex calculation to determine the risk of collision based on relative vehicle speed and calculated distance to impact. Because the detection device must be oriented so as to project ultrasonic waves at an upward angle, the resultant accuracy of detecting a low clearance obstruction may be adversely affected. In addition, the sensing angle of the device is not related in any way to the overall height of the cargo carried on the rooftop. Therefore, the Bowman detection device will yield the same alerts regardless of whether a high-profile object like a bicycle is carried on the rooftop or a low profile article such as a ladder or kayak. In other words, the detection criteria is not connected to the height of cargo extending above the roofline. The Bowman system is even less effective in addressing elongated loads like ladders. If the forward end of the ladder projects into the sensing area, it will return a perpetual “false alarm” thus rendering the system ineffective. A similar result may occur when the cargo covers the sensor, as with long loads that extend past the front edge of the roof, like boats and cargo boxes. Bowman's sensor would be covered by the load and unable to effectively alert the driver.
The prior art also teaches the installation of permanent proximity sensors to a vehicle rear or front end to act as a warning system. See, for example, U.S. Pat. No. 6,133,826 to Sparling. Such permanently affixed sensors are only effective to protect the vehicle per se. If cargo is affixed to the exterior of the vehicle in such a manner as to increase its needed clearance space, such a sensor is ineffective to warn of an oncoming overhead structure. Likewise, if a long load such as an extension ladder or a canoe extends beyond the vehicle end, these prior art proximity sensors fail to adjust for the extended length of the cargo.
Accordingly, there exists a need for a method and system for alerting the driver transporting outside-mounted cargo that the vehicle is approaching an obstruction and that a collision with the cargo is imminent. Furthermore, there is a need for such a method and system that is infinitely adaptable to difference size loads and mounting positions on the vehicle.